Conventional mattresses and box springs or foundations are of uniform firmness along their entire lengths and widths. A conventional mattress, whether of the coil spring construction or water-bed or foam or air constructions, is so soft that the upper torso of the person resting upon it tends to sag down relative to the legs. Thus, the legs are ordinarily elevated slightly relative to the lower part of the torso. This results in the lower part of the torso not being properly supported when the individual is lying in a straight line either on his back or side.
As is well known, individuals vary considerably in size, weight and proportions. However, commercially available mattresses which are made in mass production, are typically made in certain predetermined, standard sizes, such as in 75 inch, 80 inch, or 84 inch lengths and the like. Since a mattress cannot be economically made to individually fit each person who rests upon it, the mattress industry has produced mattresses which are of, pre-selected standard uniform firmnesses. That is, a particular mattress may be of a soft or a hard or a medium firmness. Hence, the individuals resting upon a mattress do not get the optimum or, in many cases, even a reasonably comfortable support for their backs, that is, the lumbar regions and adjacent portions of the body. Frequently, the lumbar region is not in full contact with the mattress so that it is not supported.
Mattresses have been made with a denser, or firmer central one-third, as compared with the upper and lower thirds, taken along their length directions. This provided a symetrical construction, wherein the upper and lower third were of the same density to provide the same support firmness, and the central one-third had a greater firmness. But this has not given adequate back support because of the wide variation in anatomy of people. Thus, it has not bee thought to be commercially feasible to adequately vary the firmness of support given by a single mattress. The invention herein relates to producing a single mattress having regions of different firmnesses proportional to the average linear weight distribution. Such assymetrical construction provides a reasonably comfortable and level support for the maximum number of people, notwithstanding some variations in their sizes and weights.